Return the value from driver_register() directly instead of storing it
in another redundant variable.
Reported-by: NZeal Robot <zealci@zte.com.cn>
Signed-off-by: Nye xingchen <ye.xingchen@zte.com.cn>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>